1. Technical Field
The present invention generally relates to cameras that compensate for undesired visual effects. More particularly, the present invention relates to rigid cameras that control perspective and depth of field.
2. Background Art
For some time now, bellows-type view cameras have been used to tailor the perspective and depth of field to the individual scene. In many cases, these bellows-type view cameras provide photographs not possible with rigid cameras; that is, cameras without a flexible bellows connecting the lens and film planes. As is known in the camera arts, bellows-type view cameras have the capability to raise and lower the lens plane relative to the film plane and vice-versa. In addition, the lens plane and/or film plane can be tilted.
In operation, translating the film or lens plane changes the field of view while maintaining constant depth of field. Tilting the film or lens plane alters the orientation and shape of the depth of field volume, but does not affect the field of view. Lens movements do not affect perspective, but require high lens coverage to avoid vignetting. In contrast, film plane movements do affect perspective, but do not require high lens coverage.
Although bellows-type view cameras control perspective and depth of field, they are expensive and generally only used by professional photographers, due to their cumbersome nature compared to rigid cameras. Attempts have been made to provide some of these control features in rigid cameras. One solution has been what are known as perspective control lenses or shift lenses. These types of lenses provide large coverage and built-in translational adjustment. However, perspective control lenses are expensive and often have inferior features relative to conventional lenses, for example, fixed focal length and manual aperture adjustment. Another solution has been to provide lenses for rigid cameras with both translation and tilt capabilities. However, these lenses are extremely expensive and the tilt feature is in one direction only.
Thus, a need exists for cost effective control of perspective and depth of field in rigid cameras.